I recently wanted to convert to smart led colour bulbs. Up until now I was using dumb led bulbs with z-wave smart toggle switches.
With going to smart bulbs they need constant power so the z-wave switches were not going to work. It might be fine for us but it would be havoc when we have guests. I think all of us here can identify with that.
I put back normal dumb 3-way / 4-way switches into the walls and installed Shelly devices. I used Shelly “detached” mode so that the smart bulbs would not lose power if a user flipped a switch. In my case I was using a mixture of Shelly 1L and 2PM because I had 3-way and 4-way to handle. Fine, all good.
Except, flickering bulbs. Nothing helped in the Shelly settings, eco mode etc. The bulbs were experiencing like a high pitched flicker. Just enough to be really annoying.
I was ready to rip out the Shellys then I discovered a solution, at least in my scenarios.
It was all to do with the white neutral wires. I was doing my hallways and as I said they were all 3-way / 4-way. Three different circuits were involved. Some of the light switches behind the scenes had two circuits, one circuit for the left hand switch and one for the right switch.
I found that my white neutral wires were all bundled together from two different circuits. Not my doing. The house came that way and it does not seem to have been a problem before.
The fix for me was to unbundle the white neutral wires and only join white wires together from the same circuit. No more flickering lights.
In my 4-way scenario the Shelly goes into the last switch box of the run just before the load. It needs constant power which was not there so I had to “borrow” constant power from another circuit in that box. The Shelly needed neutral from the circuit providing the power and not the circuit of the switches. The load would be using the line and neutral from the donor circuit.
In my 3-way (two switches) setup I did not have this complication.
Anyway, no flicker. Now on to update my automations to accommodate users flipping switches.